1. Field of the Invention
One embodiment of the present invention relates to a semiconductor device and a method for manufacturing the semiconductor device.
2. Description of the Related Art
Attention has been focused on a technique for forming a transistor including a semiconductor thin film formed over a substrate having an insulating surface (also referred to as a thin film transistor).
For example, Patent Document 1 discloses a transistor including an amorphous oxide semiconductor containing indium (In), gallium (Ga), and zinc (Zn) in a channel formation region. An oxide semiconductor has a wide bandgap and thus a transistor including an oxide semiconductor in a channel formation region has many advantages compared with a transistor including amorphous silicon, such as higher field-effect mobility, lower off-state current, and the like.
It is necessary to miniaturize a transistor in order to achieve high-speed operation, low power consumption, or high integration of a semiconductor device.
However, a channel width also decreases due to miniaturization of a transistor; thus, the on-state current is reduced. Against such a problem, a fin-type transistor has been developed in which a gate electrode is formed so as to wrap single crystal silicon formed in a fin-like structure to allow a channel formation region to be three-dimensionally structured.
A channel formation region of the fin transistor is given by a gate electrode which is provided not only on a top surface but also both side surfaces of the single crystal silicon. Accordingly, even if a semiconductor device is highly integrated with miniaturization of transistors, it is possible to increase on-state currents of the transistors.